4140 vs 4150

[Bartkowski]

I have been looking at ar-15's for a little while now, and some people say that you need 4150, some say you don't. Some say you need chrome lined bore and chamber, some say otherwise....anyway lots of opinions. So my question is, how much of an improvment is a chrome lined barrel made of 4150 steel over a chrome lined 4140?

Also, what does everyone think about a delton midlength rifle kit with a stag lower.

I understand that I will probably be directed to ar15.com, but I have been reading lots there and don't like the forum as much as THR.

 

[rangerruck]

I like chrome lined , for the ease of cleaning, the chromed versus not, I think, a lot of dudes think of it in an accuracy sense. but if you are not doing competition, or shooting a ton of rounds, causing rapid decay, I wouldn't worry about it either way. as for the other, I do not know enough to give a good opinion, allthough I have heard the 50 is much better than the 40. then again, I think this would make a big diff to an operator/contractor/competitor, etc.
If you are doing standard range/weekend stuff, i wouldn't think this would be a big diff either.

 

[highorder]

if you have a chrome lined bore, the steel underneath is far less important.


and good stuff, rangerruck.

 

[Bartkowski]

I am not doing competition, and will use the gun mostly for recreational shooting, but I still want to buy a quality firearm and have it last for years and years. I am pretty much settled on getting a chrome lined bore and chamber. The slight decrease in accuracy shouldn't effect me and I like the ease of cleaning.

I just want to know how much better 4150 is and in what way it is better.

 

[3rdpig]

Funny how some people think chrome lining in an AR is a necessity for cleaning and long life. I've got a bunch of 50+ year old hunting rifles and revolvers, none with chrome, many have spent days in rainy and wet conditions, some have thousands of rounds fired through them. None are worn out, none are rusted or pitted and none are hard to clean.

So why is a chrome lined barrel so important on a semi auto AR and not on any other kind of civilian rifle?

 

[highorder]

sheer round count on AR pattern rifles, as well as the desire to have military features, in my opinion.

 

[Bartholomew Roberts]

4150 just has a tiny bit more carbon than 4140. This translates into a slightly higher melting point, meaning that 4150 can resist extreme abuse (7 mags as fast as you can shoot them) better than 4140. If you aren't planning on doing anything like that, then not really much difference.

From what I have seen the main benefits of chrome seem to be slightly better extraction. I have just not seen the increased barrel life or easier cleaning. In fact, my stainless barrel is much easier to clean than my Bushmaster chrome-lined; but I imagine that has more to do with the mirror polish in the stainless bore than it does the chrome-lining. I would expect that the same holds true for most rifles - the nicer the bore is to begin with, the less cleaning issues you will whether chrome lined or not.

 

[RockyMtnTactical]

Chrome is a more important upgrade than 4150 steel. 4140 may not be "milspec" but it is a respectable grade of steel for barrels.

 

[Onmilo]

4140 is also a bit less expensive in bulk than 4150 and because of the properties, chrome will adhere to 4150 a bit better than 4140

I agree that 410 and 416 stainless steels are better barrel steels than 4140 or 4150 chrome moly, especially if they have been cyrogenically treated to relieve stresses.
They clean easier, resist corrosion almost as well as chrome lined standard steel barrels and are more consistently accurate.
Good stuff.

 

[Owen]

i don't think it makes much difference. If we were talking about a machine gun, or a BR rifle, we could talk. For a plinker, I don't think you'll see any difference.

 

[Soybomb]

If you're just looking for a plinker, I wouldn't worry about it.

 

[carbine85]

Mil spec calls for 4150 for increased barrel life with full auto. The 4150 under military useage is suppose to be good for several thousand rounds more then 4140. With semi-auto operation the 4140 should last just as long. You also need to consider that a tight twist and heavy bullets can wear out a barrel faster.

 

[Bartkowski]

Don't lighter bullets wear a barrel more due to the higher speed? Or is it the length of the bullet cause more metal to metal wear that makes heavy bullets worse for a barrel?